One-Pot Synthesis of Triazolo-Heterolignans: Biological Evaluation and Molecular Docking Studies as Tubulin Inhibitors.

Background: The anti-mitotic activity of podophyllotoxin derivative targeting tubulin enzyme proved them as strong polymerization inhibitors. The introduction of heteroatom along with different heteroaryl systems in naturally obtained lignans created a latitude for design of bioactive components. A novel one-pot sequential propargylation/cycloaddition reaction strategy has been followed to synthesize triazolo-heterolignans.

[4 + 2] Benzannulation of 3-Alkenylpyrroles/Thiophenes with Propargylic Alcohols: Access to Substituted Indoles, Benzothiophenes, and Aza[5]helicenes.

An efficient and practical one-pot [4 + 2] benzannulation method to produce highly substituted indoles and 1-benzothiophenes via sequential acid-catalyzed propargylation/base-mediated cycloisomerization reactions has been developed. This method allows access to differently substituted (mainly on phenyl ring) indoles and 1-benzothiophenes from the reaction of 3-alkenylpyrroles/-thiophenes as C4 synthons with 1-aryl/1-heteroaryl propargylic alcohols as C2 synthons. Interestingly, dialkynyl substrates can undergo tandem benzannulations to give substituted aza[5]helicenes in 82-83% yield.

One-Pot Sequential Propargylation/Cycloisomerization: A Facile [4+2]-Benzannulation Approach to Carbazoles.

A novel one-pot [4+2]-benzannulation approach to substituted carbazoles is accomplished by acid-catalyzed C3-propargylation of 2-alkenyl/aryl indoles with 1-aryl propargylic alcohols, followed by cycloisomerization. A variety of 2-alkenylated indoles and 2-aryl/heteroaryl indoles successfully participated in this tandem reaction with 1-aryl/heteroaryl propargylic alcohols to provide diversely substituted and annulated carbazoles, as well as an aza[5]helicene.

A thioannulation approach to substituted thiophenes from Morita-Baylis-Hillman acetates of acetylenic aldehydes.

A new protocol has been developed for the synthesis of substituted thiophenes under mild and metal-free reaction conditions via the base-promoted thioannulation of Morita-Baylis-Hillman acetates of acetylenic aldehydes with potassium thioacetate involving a tandem allylic substitution/deacetylative 5-exo-dig-thiocycloisomerization. The obtained products provide an entry to 4H-thieno[3,2-c]chromene and thieno[3,2-c]dihydroquinoline.